Turbine blade manufactured of self-carrying laminates

ABSTRACT

A turbine blade manufactured from a series of laminates each oriented in a radial-tangential plane for carrying its own centrifugal loads, and partially preformed by being initially cut into a shape suitable for stacking and bonding and being further perforated along boundaries outlining the final blade shape desired for facilitating the machine removal of excess material therefrom. Additional perforations are also incorporated in each laminate for outlining a series of built-in coolant passages.

United States Patent Tall Dec. 25, 1973 TURBINE BLADE MANUFACTURED 0F2,853,271 9/1958 Findley 416/229 x SELFLGARRYING LAMINATES 2,857,65710/1958 Wheeler 29/156.8 3,074,151 l/1963 Kroeckel 29/l56.8 Inventor:Wayne Tall, Dayton, Ohm 3,368,795 2/1968 BOlin et a1. 416/229 AssigneezThe Unimd States of America as 3,515,499 6/1970 l3eer et al. 416/95represented by the Secretary of the Pnma Examiner-Everette A. Powell Jr.

t D. 1 Force washmg C Att0rneyI-Iarry M. Herbert, Jr. et al. [22] Filed:June 27, 1972 [21] Appl. No.: 266,810 ABSTRACT A turbine blademanufactured from a series of lami- 52 US. Cl. 416/97 416/229 "ates eachmiemed a radial-tangential Plane 51 1m. (:1. "1 0111 5/08 carrying itsown centrifugal lads, and Partially P [58] Field 61 Search 416 229 23196 formed by being initially cut 3 Shape suitable for 416/97 29/1568156:8 i stacking and bonding and being further perforated alongboundaries outlining the final blade shape de- [56] References Citedsired for facilitating the machine removal of excess material therefrom.Additional perforations are also UNITED STATES PATENTS incorporated ineach laminate for outlining a series of 2,618,462 11 1952 Kane 416/229 xbuimn coolant passages 2,801,792 8/1957 Lindhagen et al..... 2,843,3557/1958 Findley 416/229 X 4 Claims, 3 Drawing Figures TURBINE BLADEMANUFACTURED OF SELF-CARRYING LAMINATES BACKGROUND OF THE INVENTION Thisinvention relates generally to the fabrication of turbine blades and, inparticular, to a laminated form of blade structure that facilitates theincorporation of relatively complex internal fluid cooling passagestherewithin.

The unique laminated turbine blade of the present invention is theresult of the recognition of the existence of certain built-indisadvantages involved in the manufacture of turbine blades by otherprevalent techniques that include, but are not necessarily limited to,machining problems for forged blade structures, difficulties in accuracyand reproductability for cored, cast designs, and that .of bonding andmaterial strength problems for laminated designs in general. Theseproblems are intensified especially when the blade structure is toincorporate provisions for fluid cooling. As will appear self-evidenthereinafter in the following summary and detailed description thereof,the new and improvded laminated blade of the present invention solvesor, at least, greatly alleviates the aforementioned difficulties ofother methods by a novel and yet simplified means to be furtherdescribed.

SUMMARY OF THE INVENTION This invention consists briefly in a turbineblade constructed from a series of laminates which are each initiallycut into a shape that is suitable for stacking and bonding together intoa preliminary blade structure of the desired overall size and shape fora particular turbine application. However, before the said stacking andbonding takes place, each of the initially cut laminates is previouslyand uniquely marked with perforations that outline the final shape ofthe blade being constructed and, in this novel manner, the subsequentremoval of the excess material therefrom to achieve the final blade formis greatly facilitated. Thus, by initially cutting each laminate into ashape suitable for stacking and bonding, and then perforating thelaminate preliminary to its stacking and bonding, a partially preformedlaminate is produced that greatly aids in both the aforementionedbonding and in the final machining of the blade. v

Another unique characteristic of the present blade resides in thespecific orientation of each of the several turbine blade-laminates in aradial-tangential plane, when assembled to the turbine-rotating diskelement, which radial-tangential orientation positively provides for andensures that each of the said laminates carries or, in other words,supports its own, pro-rata share of the centrifugal loads acting uponthe blade structure during its operation. Thus, a new and novel, and yetsimplified, built-in means has been inherently provided in the inventiveblade structure for greatly increasing its material strength at arelatively reduced weight.

Other objects and advantages inherent in this invention will becomereadily apparent hereinbelow in connection with the followingdisclosure, taken with the accompanying drawings, in which;

BRIEF DESCRIPTION OF THE DRAWINGS FIG. I is an overall schematic andperspective view, partly cross-hatched to indicate the disposition ofthe individual laminates comprising the new and improved turbine bladeof the present invention, and further showing the outline of thepreliminary perforated shape of the blade;

FIG. 2 is a second, partly schematic and plan view of one of thelaminates of the inventive blade of FIG. '1;

and

FIG. 3 represents a third, partly schematic and edge view, illustratingtwo of the laminates of the inventive blade of FIG. 1 bonded togetherand depicting one cooling hole or passage design which could be easilyutilizable therewith.

DESCRIPTION OF THE PREFERRED EMBODIMENT Referring generally to thedrawings and, in particular, to FIG. 1 thereof, the new and improvedturbine blade of the present invention, which is indicated in itssubstantially final form at 10, may be constructed, in a novel manner,from and be composed of a plurality of laminates, one of which beingdepicted in crosshatched form at 11, which laminates 11 are uniquelypartially preformed to thereby facilitate the fabrication and machiningof the turbine blade 10 into its final shape. This partial preforming isaccomplished, in part, by initially cutting each of said laminates 11into a shape that is particularly suitable for stacking and bondingtogether to thereby form a box-like structure, the outline of whichbeing indicated generally at 12 in the aforementioned FIG. 1 and whichrepresents the preliminary perforated shape of the turbine blade 10prior to its machining into its final shape. Inthe example presentedherein the shape into which each laminate 11 is to be, and has been cutis illustrated as being rectangular; however, any shape that satisfiesthe aforementioned requirement may be just as easily used and, as such,clearly falls within the scope of protection of the present invention.The initial box-like structure 12 thus formed allows and positivelyensures that an even pressure is applied to each laminate during thebonding process.

After having been initially cut, in this instance, into a rectangularshape and therefore being especially suitable for the aforementionedstacking and bonding, each laminate, as at 11, may be uniquely andfurther partially preformed by being perforated through the use of anywell-known and already-available chemical, electrical, mechanical, orcombination perforating apparatus, including the use of a Laser, alongthe boundaries outlined by the dashed lines at 13 in the view of asingle laminate in FIG. 2. With the novel use of the perforations 13,which represents the approximate final shape of the turbine blade 10,there is greatly facilitated the machine removal of the gross or excessmaterial formed by the several cross-hatched areas, indicated at 15,15a, 15b and and which are encompassed within the outline 14 of thepreliminary perforated shape of the laminate 11.

To complete the new and improved partial preforming of the inventiveturbine blade 10 and, in particular, each of the laminates lll thereof,after having previously accomplished the main perforation of each of thesaid laminates 11 to thereby form the approximate outline, as at 13, ofthe final blade shape, each laminate 11 is further perforated, whilestill in its unassembled con dition, to thereby provide the outline of,and thus produce a first, series of coolant supply holes or passages, asat 16 (FIG. 2), a second, series of blade surface holes or passages, at17, and a third, series of blade platform coolant holes, at 18. Afterproviding the outline of each of the holes or passages 16, 17 and 18,through use of the inventive perforation technique, and prior to thestacking and bonding of the laminates 11, the machine removal of theexcess material is accomplished in a relatively easy manner by cuttingalong the perforations previously marked in each laminate ll of theturbine blade and outlining the respective cooling passages. It is notedthat the cooling passages 17 and 18 extend partly into the cross-hatchedareas and 15c to the perforated outline, at 13, which represents theperforated boundary along which the initial machine cutting away of thegross material occurs.

After forming the above-mentioned cooling holes or passages 16, 17 and18, which step is quite facilitated through use of the perforatedoutline incorporated within each laminate 11, the plurality of saidlaminates are then stacked and bonded together into thepreviously-described box-like structure at 12 (FIG. 1), which, as notedhereinbefore, represents the outline of the preliminary andnow-perforated shape of the turbine blade 10. Then, through the use ofany appropriate machining apparatus, the gross material incorporatedwithin the previously-noted cross-hatched areas 15, 15a, 15b and 150 maythereafter be removed with dispatch by completely cutting along theperforations l3 outlining the final shape. The desired precise shape ofthe entire turbine blade 10 may next be completed by the utilization ofa finish or final contour machining step and/or grinding operation, asdesired.

With particular reference to FIG. 3, an adjacently positioned pair ofthe inventive laminates are indicated respectively at 11 and 11a asbeing bonded together and illustrating a specific cooling hole orpassage design that would be easily utilized with, and be formed by thepresent invention. Of course, the said cooling holes or passagesrepresent the previously described blade surface coolant holes orpassages 17 of FIG. 2. Thus, in FIG. 3, it is clearly seen that, inactual practice, the inventive perforating technique of the improvementof the present invention would be used to form matching pairs ofhemispherical passages, indicated, for example, respectively at 17a and17b, which when mated together by the bonding of the adjacentlypositioned laminates would naturally form a completed and closed hole orpassage. The coolant supply hole or passage is again indicated at 16 inthe aforementioned FIG. 3. However, as an alternative technique, eachlaminate, as at 11, could be impressed, machined, or etched entirely onone side thereof, so that a complete series of coolant fluid holes orpassages could be incorporated therewithin.

An additional unique characteristic of the structure of the presentturbine blade 10 resides in the specific orientation of the previouslydescribed bonded and partially preformed laminates, as at 11, in aradialtangential plane, when assemblied to the rotating disk member (notshown) of a particular turbine. In this connection, the said laminates 1l are each formed with interconnected, integral airfoil and dovetailportions, at 19a and 200, which collectively form the blade-airfoil anddovetail, as is indicated respectively at 19 and 20 (see FIG. 1), whichintegral airfoil and dovetail portions 19a, 20a particularly when takenin conjunction with the radial-tangential orientation thereof, ensuresthat each laminate, as at 11, is self-carrying or selfsupporting in thatit supports itself and thereby carries its own centrifugal loads throughthe dovetail 20 into the turbine-rotating disk member with which it isadapted to be assembled. Therefore, bond strength is needed only forbending shear loads, and internal pressure loads from the fluid coolingmeans, provided the internal coolant pressure is not large by comparisonwith the pressure over the blade.

Thus, a new and improved turbine blade structure has been developed bythe present invention that is both inherently stronger by beingconstructed of a series of radially oriented and bonded laminates, andis more quickly fabricated, as compared to casting and drillingprocesses, by having each laminate perforated along boundaries outliningboth the final blade shape and a series of cooling passages to beincorporated therein for thereby providing for the relativelyinexpensive machine removal of excess material therefrom.

I claim:

1. In a method for facilitating both the production of a turbine bladeof increased strength, greatly simplified construction, and relativelyreduced weight, and further specifically and positively providing forand having built-in provisions for fluid cooling, the steps comprising;initially cutting each of a plurality of individual laminates into anoverall rectangular or other specific shape most suitable both forstacking and for ensuring, and providing for the application of a moreuniform and positive bonding pressure between adjacentlypositionedlaminates in the completed stack; facilitating the subsequent final andcomplete fabrication of the turbine blade-by initially, and partiallyand separately preforming each of the said individual and precutlaminates, before their stacking and bonding together, by impressingtherewithin both the approximate and general overall outline of thefinal blade shape to be produced, and complementary matching halfportions, with respect to the adjacently positioned laminates in acompleted stack, of each of a plurality of built-in coolant passages ofvarying disposition and complexity to be inherently incorporated in thefinal blade structure prior to, and as a result of the final assemblythereof; then removing excess material by machine cutting along thepreviously impressed outlines of, and thereby completing the initialpreliminary production of the said complementary matching half portionsin preparation for the subsequent formation of the said built-in coolantpassages during the final fabrication of the turbine blade; thereafterpartially fabricating the turbine blade and completing the fonnation ofthe said built-in coolant passages by stacking and bonding together saidplurality of individual and now-partially preformed laminates into anoverall laminated box-like structure approximating the overall size andshape, and containing the previously impressed outlines in each of thesaid laminates of the turbine blade to be produced therefrom; and,finally, completing the fabrication of the turbine blade, first, byinitially machine removing the gross material from the said box-likestructure by cutting along and completely through the saidpreviously-impressed outlines of the approximate final blade shapeinitially formed in each of the said individual and now-alignedlaminates during the partial preformation of each thereof to therebyachieve the rough blade form in final preparation for its subsequentfinish contour machining and/or grinding operations.

2. In a method for producing a turbine blade as in claim 1, wherein thestep of facilitating fabrication of the turbine blade comprisesperforating each laminate along outlines of both the final blade shapeand the built-in coolant passages.

3. In a method for producing a turbine blade as in claim 2, wherein thestep of perforating each laminate during the partial preforming thereofto thereby facilitate fabrication of the turbine blade includes theoutline and thereby the preparation of the provision of a turbine bladestructure having an airfoil portion, and a dovetail portion to beintegrally formed with the airfoil inherently stronger laminated turbineblade structure.

1. In a method for facilitating both the production of a turbine bladeof increased strength, greatly simplified construction, and relativelyreduced weight, and further specifically and positively providing forand having built-in provisions for fluid cooling, the steps comprising;initially cutting each of a plurality of individual laminates into anoverall rectangular or other specific shape most suitable both forstacking and for ensuring, and providing for the application of a moreuniform and positive bonding pressure between adjacently-positionedlaminates in the completed stack; facilitating the subsequent final andcomplete fabrication of the turbine blade by initially, and partiallyand separately preforming each of the said individual and precutlaminates, before their stacking and bonding together, by impressingtherewithin both the approximate and general overall outline of thefinal blade shape to be produced, and complementary matching halfportions, with respect to the adjacently positioned laminates in acompleted stack, of each of a plurality of built-in coolant passages ofvarying disposition and complexity to be inherently incorporated in thefinal blade structure prior to, and as a result of the final assemblythereof; then removing excess material by machine cutting along thepreviously impressed outlines of, and thereby completing the initialpreliminary production of the said complementary matching half portionsin preparation for the subsequent formation of the said built-in coolantpassages during the final fabrication of the turbine blade; thereafterpartially fabricating the turbine blade and completing the formation ofthe said built-in coolant passages by stacking and bonding together saidplurality of individual and now-partially preformed laminates into anoverall laminated box-like structure approximating the overall size andshape, and containing the previously impressed outlines in each of thesaid laminates of the turbine blade to be produced therefrom; and,finally, completing the fabrication of the turbine blade, first, byinitially machine removing the gross material from the said box-likestructure by cutting along and completely through the saidpreviously-impressed outlines of the approximate final blade shapeinitially formed in each of the said individual and now-alignedlaminates during the partial preformation of each thereof to therebyachieve the rough blade form in final preparation for its subsequentfinish contour machining and/or grinding operations.
 2. In a method forproducing a turbine blade as in claim 1, wherein the step offacilitating fabrication of the turbine blade comprises perforating eachlaminate along outlines of both the final blade shape and the built-incoolant passages.
 3. In a method for producing a turbine blade as inclaim 2, wherein the step of perforating each laminate during thepartial preforming thereof to thereby facilitate fabrication of theturbine blade includes the outline and thereby the preparation of theprovision of a turbine blade structure having an airfoil portion, and adovetail portion to be integrally formed with the airfoil portion andbeing further adapted for attachment with a turbine-rotating diskmember.
 4. In a method for producing a turbine blade as in claim 3,wherein the step of partially fabricating the turbine blade includesstacking and bonding together of the plurality of laminates with theirorientation being in a radial-tangential plane for thereby positivelyensuring that each laminate supports its own centrifugal loads throughthe integral dovetail portion into tHe rotating disk member of theturbine and thus provides an inherently stronger laminated turbine bladestructure.